纳米Ni/SiO_2介孔复合体的制备与超顺磁性  

Preparation and Superparamagnetism of Nano-Ni/mesoporous SiO_2 Composites

作　　者：樊三强[1] 蔡维理[1] 牟季美[1] 陈慧余[2] 

机构地区：[1]中国科学技术大学材料科学与工程系,合肥230026 [2]中国科学技术大学物理系,合肥230026

出　　处：《Chinese Journal of Chemical Physics》2001年第2期205-210,共6页化学物理学报（英文）

基　　金：国家自然科学基金!资助项目 (19974 0 4 1)&&

摘　　要：采用溶胶—凝胶法制备了含Ni2 + 的SiO2 干凝胶 ,再通过化学还原得到了纳米Ni/SiO2 介孔复合体。从样品的透射电子显微镜观测结果可估算出 ,介孔复合体中Ni粒子的尺寸约为 11～ 12nm。样品的磁性测量结果表明 ,与通常的Ni纳米颗粒相比 ,纳米Ni/SiO2 介孔复合体中纳米Ni粒子的粒径在大于理论计算的纳米Ni粒子的临界尺寸时 ,仍能够保持超顺磁状态。在一定温度范围内 ,提高还原温度有利于复合体中纳米Ni粒子向超顺磁状态转变。Nano-Ni/mesoporous SiO 2 composites were obtained by reducing Ni 2+ -doped SiO 2 xerogels in H 2, which were prepared via a sol-gel route. The average size of nano-Ni particles in mesoporous composites was estimated at 11～12nm from TEM (Transmission Electron Microscope) photographs. The results of magnetic measurements show that compared with the conventional nano-Ni particles, the Ni particles in nano-Ni/mesoporous SiO 2 composites remain superparamagnetic state when their particle size is larger than the critical size of Ni calculated theoretically. Elevation of the reduction temperature promotes transformation of nano-Ni particles in mesoporous composites into the superparamagnetic state within a certain range of temperature.

关 键 词：超顺磁性 介孔复合体 磁各向异性 镍 二氧化硅 纳米复合体 制备 

分 类 号：TB383[一般工业技术—材料科学与工程] TB333